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Chipping and Filing.                         209

drilled and slotted. A Lead Hammer, for use on finished
work; a Hack Saw; and an adjustable spanner are also
advisable. Round holes are clearied by the Parallel Rimer
in Fig. 231, and taper holes by means of a Taper Rimer
similarly constructed.

General Processes.—Chipping.—Although hand pro-
cesses cannot well be taught on paper, a general idea may yet be
obtained. We will consider ourselves provided with a cubical
block of metal, and that it is desired to remove a rather large
amount of material from one of the surfaces. We commence by
placing the block on the marking-off table, and, chalking the
edges, scribe a line round as shewn at Fig. 2190, to indicate the
layer to be removed. This done we place the work in the vice
and chip with flat chisel a chamfer along the edge of the block,
nearly down to the scribed line, as at B, and make this fairly
straight with a rough file. Now the cross-cut chisel is applied,
and with it the cross grooves are cut as at c, each groove being
tried with a straight edge, to make sure it is not carried too far
below the general surface. We are now in a position to com-
mence the removal of the strips that remain by means of the flat
chisel, constantly trying the work with the straight edge, until the
whole is as perfect as the chisel can make it. The position of
the workman and the angle of chisel are shewn in Fig. 220, and
practice only will shew the steepness of angle required for the
deep cut, and the shallower angle for the lighter cut

Filing.—The file is next applied, and the various * cuts'
used in order from bastard to smooth. True filing requires con-
siderable skill, the tendency to the production of a convex surface
being very great The back stroke needs no pressure, as the
teeth do not then cut; but during the forward stroke all possible